Known in the art an electrosurgical instrument which is in fact a knife either straight or bent at 30 degrees, serving as an active electrode connected to a source of diathermic current (cf. an advertisement prospectus for "The 3C-3O r.f. electrosurgical apparatus").
The aforementioned knife-like instruments are monoactive, i.e., requiring the other passive plate-electrode, applied to the body of the patient operated upon a certain distance apart from the knife.
Use of a passive electrode in surgical procedures leads to complications, viz., damaging the organs and tissues on the path of an r.f. current flowing from an active knife-electrode to a passive electrode, or burns of tissues situated under the passive electrode. Furthermore, it is due to r.f. current dispersion in the tissues lying between the knife and the passive electrode and useless heating of the tissues that operative procedures on internal organs become uncontrolled and proceed unstably. In addition, the instrument is to be additionally cleaned of the coagulate deposit.
Another electrosurgical instrument is known to comprise a cutting working portion shaped as two ring-electrodes separated with an insulant disk, a mechanical actuator to impart rotation to the working portion, and current leads, each interacting, through its electric contact, with the respective ring electrode. The electric contacts are made as springy knives interacting with the end faces of the electrodes (cf. USSR Inventor's Certificate No. 639,561 published 1978).
In the aforesaid instrument both of the ring electrodes are active, and the length of path of an r.f. current from electrode to the other is as short as fractions of a millimeter. Coagulate deposit is removed from the electrodes by knife-shaped current leads. Getting the active electrodes rid of coagulate deposit and shaping the cutting working portion as a rotary disk makes it possible to establish a stable r.f. current field within the operative wound, which adds much to the efficacy of the surgery performed.
However, the known biactive electrosurgical instrument enables mostly surgery on the parenchymatous organs, and its function boils down to bloodless cutting of the parenchyma without slitting open the lumen of major blood vessels, which is attained due to the instrument's cutting lips being shaped as an oval. Thus, the heretofore-known electrosurgical instrument produces a destructive effect upon the tissue due to the action of a diathermic current alone, without a mechanical cutting effect, which renders the instruments inapplicable for bloodless surgery on soft (muscular) tissues, as well as for dissection of the skin, fasciae and ligaments.